This is revisionist history based on revisionist science. Most of the North and South American populations were killed by plagues before European colonization began.
As in Asia and Africa, medical and technological advancements by whites permitted those populations to grow much larger than nature had permitted. The idea that North America was teeming with a billion Indians before Honky McCracker arrived is just absurd; their primitive societies prevented the land from sustaining dense masses of people. Central America sustained larger populations (with actual cities) because it is much more fertile. While we have some stonework in the southwest from Indians, there is a reason there are no large former settlements throughout most of the US.
Some archeologists suspect the Plains Indians didn’t even exist when first whites arrived on the east coast, and they are descended from those pushed westward. They maintain there is no archeological record to support the contention that the Plains Indians existed yet in the seventeenth century. That lifestyle (following buffalo herds) sustained minimal populations in comparison to the Aztec or Incas.